We have identified more than 40,000 single nucleotide polymorphisms (SNPs) in 16 samples of Aedes aegypti from around the world, as well as a sample of its closest relative, Ae. mascarensis. This was done using a technique that is efficient in identifying SNPs (RAD-tags), but this methodology is not applicable for routine genotyping. We propose to develop a SNP chip based on these identified SNPs that can be applied routinely for reliable genotyping in a time- and cost-effective manner. Our own interests are on the population genetics and ancestry level and we will focus on a chip designed specifically for our studies. A by-product of the work will be more extensive data upon which other groups could design a chip for genome wide association studies; all data will be publically available. The first part of the project is development of the population chip. This will proceed i three steps: (1) From the >40,000 available SNPs, identify ~5,000 that have the most variation across the species' distribution and reliably genotype on SNP chips. (2) From these 5,000, use theoretical analyses to identify ~750 that capture the population/ancestry information of the complete data set. (2) Perform crosses to confirm the Mendelian (single-copy, nuclear) nature of these 750, with the expectation that at least 500 will be Mendelian and form the basis of the population SNP chip. The second part of the project is application of this chip. Four projects are proposed: (1) Perform a global population genetics study to determine the genetic diversity, patterns, and relatedness of populations from around the world; collections are already in hand for this. (2) Study five ecologically and geographically diverse populations through time to determine the genetic stability of Ae. aegypti populations as well as effective population sizes. (3) Genotype common lab strains to determine where they fit into the genetic diversity of the species and how homogeneous or heterogeneous they are among isolates from different laboratories. (4) Genotype populations in West Africa that have recently colonized urban centers and compare them to nearby sylvan populations that are the likely source of the domestication event; independent replicate cases will allow us to identify parallel genetic changes that would give insight into the genetic nature of the domestication process.